Human neural systems that mediate visual perception, attention and memory went investigated in the intact brain with functional brain imaging. Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) were used to measure precisely localized hemodynamic changes associated with the performance of selected visual perceptual and mnemonic tasks. These hemodynamic changes are indices of local changes in neural activity. Human extrastriate visual cortex like that of the macaque monkey, was found to be organized into a ventral object vision stream and a dorsal spatial vision stream. Visual working memory was found to be associated with neural systems in prefrontal cortex, and different prefrontal areas were associated with different aspects of visual working memory. The encoding of new long-term memories for faces was associated with right hippocampal activity whereas retrieval of these memories was not. Non-overlapping neocortical networks associated with storage and retrieval were also demonstrated indicating that memory storage and retrieval involve anatomically dissociable operations.